I'm replacing my brake cables.- Mtbr.com
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  1. #1
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    I'm replacing my brake cables.

    Should I just use my old ones to measure out the length? I can't think of any other questions to ask relating to this task.

  2. #2
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    Just leave the cables full length until they are installed and adjusted. Then cut and cap or solder them. Best tip, use a circular cable cutter to keep them from unraveling.
    Tight + Twisty = Tasty
    Earn your turns!

  3. #3
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    Do what Fly Rod says for inner cables. Leave them full length until they are threaded through and adjusted. Cut last.

    For outer cables, sure, measure to match the existing set. That's the easiest way at first. Once you've done a few replacements, you'll get comfortable in sizing everything from scratch. I usually go by the old cables unless I've mislaid them, or unless I wasn't happy with their length.

    Edit: "outer cable" = "housing".

  4. #4
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    Is there anything wrong with just cutting them the shortest length that'll still allow my bars to turn all the way?

  5. #5
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    Dear mmik,
    Yes! You want smooth gentle bends in the cable "loop". Short bends make for more friction between the inner and outer cable housing. So just a little bit more than "the shortest length that will allow your bars to turn."

  6. #6
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    Hmm... I get what you're saying, but that makes me wonder exactly how short I should go.

  7. #7
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    Quote Originally Posted by mmik
    Hmm... I get what you're saying, but that makes me wonder exactly how short I should go.
    Better a hair long than a hair short. It you go too short the brakes will be applied when you turn the bars too far.

  8. #8
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    Yea I plan to leave slack in it. I guess what I'll do when I get a chance is take a picture of the cables, just holding them up, and ask if I should cut them shorter or longer than what I'm showing.

    By that I mean I'll hold the cables at an estimated length against my bike, so you can see in the picture how much slack there will be.

  9. #9
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    Just put the housings in the stops w/o the cable and turn the bars. If the housing pulls out (at all) at full turn it's too short. Holding them in a picture won't really show much.

  10. #10
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    -If you cut the cable before you install it, you have a chance of a loose wire coming unraveled when you push the cable through the housing. thats why everyone is correctly saying to cut last.
    -I find that a dremel with a cut off disc works well for cutting cable and housing, if you don't have the cutters. Pliars or wire cutters usually fray the cable and squish the housing, making things a mess.
    -If the housing is long enough to let your bar turn freely without binding, then it has a gentle enough curve to it.
    -If you dont have cable end caps, dipping the end in elmers glue, shoe goo or silicone works well.

  11. #11
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    Quote Originally Posted by mmik
    Is there anything wrong with just cutting them the shortest length that'll still allow my bars to turn all the way?
    That's pretty much what I do. Usually I take a guess to start with. Then I hold the uncut housing in place whilst turning the bars 180 degrees. I adjust as needed to leave minimal slack when the bars are turned completely around. Then I cut.

    You'll never do a 180 degree turn while riding, unless you're crashing. Minimal slack at 180 degrees will generally leave plenty of slack for normal riding positions.

    Edit: Make sure you test 180 degrees in both directions -- left and right.

  12. #12
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    Can I get some example pics maybe of acceptable slack? I know I'm being picky here, but I don't want to screw up cutting this and need to buy more. My other bike's cables are really short, but they're hydraulic, so I assume I can't run cable as short.

  13. #13
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    Check out this thread: http://forums.mtbr.com/showthread.php?p=4243905&page=17. The white bike with blue accents has nice cables. There is a carbon one with red cables where some of the cables look a little long to me.

  14. #14
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    Quote Originally Posted by mmik
    Can I get some example pics maybe of acceptable slack?
    Someone will probably critique my cable routing, but the first three images in the following album might help:

    http://www.facebook.com/media/set/fb...9&l=a447dbfc74

    In the image where I'm 180 to the left, I really have the cable a bit shorter than I would prefer. It doesn't bind up though, so I'm running with it for now.
    Last edited by JonathanGennick; 04-27-2011 at 08:44 AM.

  15. #15
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    Housing length is not that critical. there are probably only 17 million photos on this site you could look at. Get in the ball park, make sure its long enough, and cut it. Get it over with.

  16. #16
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    Smilinsteve has a point. If you're going to do-it-yourself, you've got to get past the angst from making a small blunder. Make a decision. Cut. If the length works, you've learned something. If you find the housing is too short, you've learned something. Worst case you pay a few bucks in "tuition" for some extra housing.

  17. #17
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    Quote Originally Posted by mmik
    Can I get some example pics maybe of acceptable slack? I know I'm being picky here, but I don't want to screw up cutting this and need to buy more. My other bike's cables are really short, but they're hydraulic, so I assume I can't run cable as short.
    The first time I ran brake (and derailleur) cables, I went to google image search and typed in the make and model of my bike frame. I just browsed through all of the photos paying attention to the cable routing and how much slack at the headtube and derailleur.

    Plus, I found a couple of nifty routing alternatives I hadn't thought about...

  18. #18
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    This is my old cable still in place, but I'm wondering what I should do here to best secure the cable. See how it has that long empty space between the two rests? (which I guess I zip-tie the cable to; at least that's how the old cable is held on.)

    I don't want it flapping around, but I don't want to ziptie the center of the cable to the frame and scuff it up. Not that I care THAT much about scratches. : P


  19. #19
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    It looks like those rests were designed for hydraulic hose, which of course has to be run full length from the levers to the brake. There is usually a plastic clip that goes over the hose and clips to the bottom part, like these
    http://www.universalcycles.com/shopp...346&category=7
    but a zip tie works fine.

    For a frame designed for cable brakes, those rests would be housing stops, and there would be bare cable running between the stops.

    If you think the housing is too floppy, you can just zip tie the housing directly to the frame, or you can just leave it as is.
    Or you can buy stick on hose guides here:
    http://www.universalcycles.com/shopp...12&category=13
    or
    http://www.universalcycles.com/shopp...31&category=13

    Or you can add bolt on housing stops to your frame, to eliminate some of that housing which would make your brakes work a bit smoother:

    http://www.universalcycles.com/shopp...754&category=7

  20. #20
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    Well I have the front cable put in and I have two problems:

    1.) I can pull the lever all the way to the bar and the brake is just barely applied. (tire still rubs through it)
    2.) at the start of me pulling back on the brake handle, the housing twitches a bit instead of pulling on the brake pads,

    I have disk brakes btw in case that helps you help me.

  21. #21
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    OK THIS IS EXACTLY WHY I DIDNT WANT TO DO THIS ON MY OWN

    I even had the LBS cut the housing the correct length for me and I STILL SCREWED IT UP.

    Nowhere did it say they two wires given are different lengths, and I cut the longer one for the front brake and I'm stuck with a back one that's too short. I'm out 35 dollars because I had 10 different people online and off insisting I can do this crap on my own.

    brilliant.

  22. #22
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    I hereby suggest you go to your LBS for future repairs.

  23. #23
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    This is exactly what happens every time I try to do something myself; I end up destroying something. This happened both times I've tried to replace my chain, as well. I don't understand how I'm so bad at everything.

  24. #24
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    I wouldn't be too hard on yourself. Some people are mechanically inclined and some are not. It's not a bad thing. Just make sure to factor in labor costs and you're good to go.

  25. #25
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    You can buy a replacement cable for probably less than 5 bucks. Even hardware stores have them.
    Anyone can do what you are trying to do, but you have to learn how. You learn by doing. If you make a mistake, don't consider it failure, consider it a learning experience.
    When you have the job complete, you will have succeeded, no matter if you had to buy an extra cable or whatever, and you will be much better at it the next time.

  26. #26
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    But I cut 2 inches or so off of the housing to try to make it fit the cable before realizing I didn't have that kind of play-room. I could post pics of how short the housing is right now if you want to decide if it's too short or not for me, but it looks like it is.

  27. #27
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    Hey I've made those same mistakes. Cables are usually universal so they can be used front or rear. Selling a short cable for front use only is dumb, but unfortunately sometimes thats what you get.
    You could replace the stuff you cut too short and still probably save money compared to paying for someone else's labor. IF it was me, I would keep at it until I got it. I just want to know I can do things, and will not give up. But you have to believe in yourself. I have gotten to the point (after years of being a handy man), that I will try almost any project with complete confidence I can do it, even if I never have before.

    Start small with stuff like brake cables, and increase your abilities as time goes on. The other option is to have no mechanical skills your whole life, and live with leaky faucets, doors that don't close, brakes that rub, light switches that don't work, etc, unless you end up rich enough to pay someone for every minor adjustment in your life.

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